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Studies show need for TB research

May 19, 2010 11:13pm

Standardizing the approach to tuberculosis diagnosis and treatment that is recommended by the World Health Organization allowed more than 36 million people to be cured between 1995 and 2008, averting up to 6 million deaths. But TB remains a severe global public health threat, and scientists say superbug strains of the disease are gaining ground in some countries, according to a series of studies in The Lancet.

While existing technologies can help in diagnosing the disease, they often aren't available in many developing countries; therefore, greater investment in research and development of new drugs and vaccines is needed, the authors maintain. There are more than 9 million new cases every year worldwide, and the incidence rate is falling at less than 1 percent per year, the study "Tuberculosis control and elimination 2010-50: cure, care, and social development" notes. And the authors worry that the long-term elimination target set for 2050 will not be met with present strategies and instruments.

"Although progress has been made to reduce global incidence of drug-susceptible tuberculosis, the emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis during the past decade threatens to undermine these advances," Neel Gandhi of New York's Yeshiva University and Paul Nunn of the WHO caution in another study in the series. But many countries aren't responding fast enough to this threat; of the estimated 440,000 cases of MDR TB that occurred in 2008, just 7 percent were detected and reported to the WHO. And only a fifth were treated according to WHO standards, the authors maintain.

Developing nations tend to carry much of the disease burden. India and China carry nearly 50 percent of the global burden, followed by Russia at 9 percent.

TB is caused by the Mycobacterium tuberculosis bacteria and can be cured with antibiotics, but they must be taken daily for months to be effective and public health funding cuts in some countries may mean fewer drugs are available, Reuters notes. Because people do not always take the drugs properly, MDR-TB strains are starting to take hold and the WHO says there is an urgent need for countries to set up laboratories to fight it. The AFP notes that most types of TB can be cured with about $13 worth of medicine if diagnosed early. But when patients fail to complete a treatment, the Mycobacterium tuberculosis germ develops a resistance to frontline drugs such as isoniazid and rifampicin.

The authors are particularly concerned about patients co-infected with HIV, who are much more likely to progress to active TB after initial infection. They also are the first to show active drug-resistant TB after transmission in an outbreak, while HIV-negative individuals may become latently infected and show symptoms years later, if at all, the authors say.

Some companies are looking for ways to combat TB in these immunocompromised patients. Last week, FierceVaccines reported on Spain's Archivel Farma, which is testing a therapeutic vaccine that could help in the fight against latent tuberculosis. The treatment, called RUTI, is being tested in conjunction with an antibiotic and is about to be studied in patients in a South African Phase II trial. The trial will enroll 96 individuals with or without concomitant HIV infection. Also, the Aeras Global TB Foundation and Crucell announced in April the start of a Phase II clinical trial of the jointly developed vaccine candidate AERAS-402/Crucell Ad35 in HIV infected adults.